System and method for mapping

ABSTRACT

A computer implemented method for updating a point map on a system having first and second communicatively coupled hardware components includes the first component performing a first process on the point map in a first state to generate a first change. The method also includes the second component performing a second process on the point map in the first state to generate a second change. The method further includes the second component applying the second change to the point map in the first state to generate a first updated point map in a second state. Moreover, the method includes the first component sending the first change to the second component. In addition, the method includes the second component applying the first change to the first updated point map in the second state to generate a second updated point map in a third state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/519,513, filed on Jul. 23, 2019, entitled “SYSTEM AND METHOD FORMAPPING, which claims priority to U.S. Provisional Application No.62/702,322, filed on Jul. 23, 2018, entitled “SYSTEM AND METHOD FORMAPPING.” The contents of the aforementioned patent applications arehereby expressly and fully incorporated by reference in their entirety,as though set forth in full.

FIELD OF THE INVENTION

The present disclosure relates to multiple component mapping and mapsynchronization systems, and method of mapping and synchronizing mappingacross multiple components using same.

BACKGROUND

Modern computing and display technologies have facilitated thedevelopment of “mixed reality” (MR) systems for so called “virtualreality” (VR) or “augmented reality” (AR) experiences, wherein digitallyreproduced images or portions thereof are presented to a user in amanner wherein they seem to be, or may be perceived as, real. A VRscenario typically involves presentation of digital or virtual imageinformation without transparency to actual real-world visual input. AnAR scenario typically involves presentation of digital or virtual imageinformation as an augmentation to visualization of the real world aroundthe user (i.e., transparency to real-world visual input). Accordingly,AR scenarios involve presentation of digital or virtual imageinformation with transparency to the real-world visual input.

MR systems typically generate and display color data, which increasesthe realism of MR scenarios. Many of these MR systems display color databy sequentially projecting sub-images in different (e.g., primary)colors or “fields” (e.g., Red, Green, and Blue) corresponding to a colorimage in rapid succession. Projecting color sub-images at sufficientlyhigh rates (e.g., 60 Hz, 120 Hz, etc.) may deliver a smooth color MRscenario in a user's mind.

Various optical systems generate images, including color images, atvarious depths for displaying MR (VR and AR) scenarios. Some suchoptical systems are described in U.S. Utility patent application Ser.No. 14/555,585 filed on Nov. 27, 2014, the contents of which are herebyexpressly and fully incorporated by reference in their entirety, asthough set forth in full.

Head-worn display devices that enable AR/MR provide concurrent viewingof both real and virtual objects. With an “optical see-through” display,a user can see through transparent (or semi-transparent) elements in adisplay system to view directly the light from real objects in anenvironment. The transparent element, often referred to as a “combiner,”superimposes light from the display over the user's view of the realworld, where light from by the display projects an image of virtualcontent over the see-through view of the real objects in theenvironment. A camera may be mounted onto the head-worn display deviceto capture images or videos of the scene being viewed by the user.

Current optical systems, such as those in AR/MR systems, opticallyrender virtual content. Content is “virtual” in that if does notcorrespond to real physical objects located in respective positions inspace. Instead, virtual content only exist in the brains (e.g., theoptical centers) of a user of the head-worn display device whenstimulated by light beams directed to the eyes of the user.

Some AR/MR systems use maps (e.g., topological maps, geometric maps,sparse point maps, etc.) of a real world environment to generate apassable world model for an AR/MR scenario. The passable world modelfacilitates interactions involving real world objects in the real worldenvironment such (e.g., displaying a virtual object on a real worldsofa). A sparse map is a fundamental building block for computing visionpose relative to a “stable” coordinate system. Environmental featuresbecome reference points in a 3D sparse map. Positions of referencepoints relative to the sensors defined the position or pose of thesensors. Sparse map can be built using data from multiple systemcomponents. A spare map allows tracking to facilitate permanence forvirtual objects in a real world environment (“pixel stick”). Some AR/MRmapping related methods involve localization of the AR/MR device usingtopological maps to determine a position and pose of a user and/or anAR/MR device. Some AR/MR mapping related methods involve modeling realworld objects of the AR/MR device using geometric maps to allow moreaccurate and realistic presentation of virtual objects. Some AR/MRsystems generate and/or update maps of a (possible dynamic) real worldenvironment using Simultaneous Localization and Mapping techniques.

As an example, localization allows a user wearing a head-worn displaydevice to view a virtual object on the display while walking around anarea where the virtual object appears. With updated position and posedata, the virtual object can be rendered for each viewpoint, giving theuser the perception that they are walking around an object that occupiesreal space. If the head-worn display device is used to present multiplevirtual objects, measurements of head pose can be used to render thescene to match the user's dynamically changing position and pose andprovide an increased sense of immersion.

Maps can be generated, modified, and/or optimized using many methods andtechniques. Some of these techniques involve new data. One such group ofnew data techniques is collectively called tracking and includesupdating of map-point statistics, which may trigger map point deletion.Another new data technique is Visual Inertial Odometry (“VIO”), whichincludes applying inertial constraints to a sparse point map. Stillanother group of new data techniques is collectively called mapping,which includes inserting new keyrig frames (“keyframes” or “rigframes”),map points and observations. Yet another group of new data techniques iscollectively called relocalization, which includes adding new orbfeatures and Bag of Words (“BoW”) indices. Another group of new datatechniques is collectively called map merge, which includesincorporating sparse map data from a different AR/MR session. Stillanother group of new data techniques is collectively called joint denseoptimization, which includes incorporating dense map data.

Other mapping techniques involve optimization of existing maps. One suchgroup of optimization techniques is collectively called bundleadjustment, which includes modifying sparse map geometry and onlinecalibration. Another group of optimization techniques is collectivelycalled loop closure, which includes modifying sparse map geometry.

Various AR/MR mapping related methods and techniques are described inU.S. Utility patent application Ser. No. 14/705,983 filed on May 7, 2015and Ser. No. 14/704,844 filed on May 5, 2015, the contents of which arehereby expressly and fully incorporated by reference in their entirety,as though set forth in full.

As described above, mapping facilitates AR/MR system functions.Synchronizing maps across components of multiple component AR/MR systems(e.g., a head-worn display (“wearable”) and a belt-worn or body-wornprocessing component (“power pack”)) facilitates a coherent andconsistent AR/MR scenario. Map synchronization implicates certain systemlimitations such as processing power, memory, bandwidth, data sources,latency, and multiple operating systems, processors and architectures.

SUMMARY

In one embodiment, a computer implemented method for updating a pointmap on a system having first and second communicatively coupled hardwarecomponents includes the first component performing a first process onthe point map in a first state to generate a first change. The methodalso includes the second component performing a second process on thepoint map in the first state to generate a second change. The methodfurther includes the second component applying the second change to thepoint map in the first state to generate a first updated point map in asecond state. Moreover, the method includes the first component sendingthe first change to the second component. In addition, the methodincludes the second component applying the first change to the firstupdated point map in the second state to generate a second updated pointmap in a third state.

In one or more embodiments, the method also includes the secondcomponent sending the second change to the first component. The methodfurther includes the first component applying the second change to thepoint map in the first state to generate the first updated point map inthe second state. Moreover, the method includes the first componentapplying the first change to the first updated point map in the secondstate to generate the second updated point map in the third state. Themethod may also include the first component generating a change orderbased on the first and second changes, and the first component applyingthe second change to the point map in the first state before apply thefirst change to the updated point map in the second state based on thechange order. The first component applying the second change to thepoint map in the first state may include the first component generatinga pre-change first state. The first component applying the first changeto the first updated point map in the second state may include the firstcomponent generating a pre-change second state. The second componentapplying the second change to the point map in the first state mayinclude the second component generating a pre-change first state, andthe second component applying the first change to the first updatedpoint map in the second state may include the second componentgenerating a pre-change second state.

In one or more embodiments, the method also includes the first componentgenerating a change order based on the first and second changes, and thefirst component sending the change order to the second component. Themethod may also include the second component applying the second changeto the point map in the first state before applying the first change tothe updated point map in the second state based on the change order. Thefirst process may be selected from the group consisting of tracking, mappoint deletion, VIO, mapping, insertion of new keyframe/key rigframe,insertion of new map point, insertion of new observation, bundleadjustment, modification of sparse map geometry, online calibration,relocalization, adding new orb feature; add new BoW index; loop closure;modify sparse map geometry; map merge; and joint dense optimization.

In one or more embodiments, the point map corresponds to a physicallocation in which the system is located. The physical location may be aroom or a cell in a room. The point map may be a portion of a largerpoint map.

In one or more embodiments, the first component is a head-mountedaudio-visual display component of a mixed reality system, and the secondcomponent is a torso-mounted processing component of the mixed realitysystem. The method may also include the second component reconciling thefirst and second changes before applying the second change to the pointmap in the first state.

In one or more embodiments, the first and second components arecommunicatively coupled to a third component. The method also includesthe third component performing a third process on the point map in thefirst state to generate a third change. The method further includes thefirst and second components sending the first and second changes to thethird component, respectively. Moreover, the method includes the thirdcomponent applying the third change to the second updated point map inthe third state to generate a third updated point map in a fourth state.The first component may be a head-mounted audio-visual display componentof a mixed reality system, the second component may be a torso-mountedprocessing component of the mixed reality system, and the thirdcomponent may be a cloud based processing component. The method may alsoinclude the second component receiving the first change from the firstcomponent before generating the second change. The second component mayinclude removable media for data storage.

In another embodiment, a mixed reality system includes a head-mountedaudio-visual display component, and a torso-mounted processing componentcommunicatively coupled to the display component. The display componentis configured to perform a first process on a point map in a first stateto generate a first change, and send the first change to the processingcomponent. The processing component is configured to perform a secondprocess on the point map in the first state to generate a second change,apply the second change to the point map in the first state to generatean first updated point map in a second state, and apply the first changeto the first updated point map in the second state to generate a secondupdated point map in a third state.

In one or more embodiments, the processing component is furtherconfigured to send the second change to the display component. Thedisplay component is also configured to apply the second change to thepoint map in the first state to generate the first updated point map inthe second state and apply the first change to the first updated pointmap in the second state to generate the second updated point map in thethird state. The display component may also be configured to generate achange order based on the first and second changes, and apply the secondchange to the point map in the first state before apply the first changeto the updated point map in the second state based on the change order.

In one or more embodiments, the display component is further configuredto generate a change order based on the first and second changes, andsend the change order to the processing component. The processingcomponent may also be configured to apply the second change to the pointmap in the first state before applying the first change to the updatedpoint map in the second state based on the change order. The firstprocess may be selected from the group consisting of tracking, map pointdeletion, VIO, mapping, insertion of new keyframe/key rigframe,insertion of new map point, insertion of new observation, bundleadjustment, modification of sparse map geometry, online calibration,relocalization, adding new orb feature; add new BoW index; loop closure;modify sparse map geometry; map merge; and joint dense optimization.

In one or more embodiments, the point map corresponds to a physicallocation in which the system is located. The physical location may be aroom or a cell in a room. The point map may be a portion of a largerpoint map.

In one or more embodiments, the processing component is furtherconfigured to reconcile the first and second changes before applying thesecond change to the point map in the first state. The display andprocessing components may be communicatively coupled to an onlinecomponent. The display and processing components may be configured tosend the first and second changes to the online component, respectively.The online component may be configured to perform a third process on thepoint map in the first state to generate a third change, and apply thethird change to the second updated point map in the third state togenerate a third updated point map in a fourth state.

In one or more embodiments, the display component includes a displaycomponent map manager configured to generate a change order, applychanges based on the change order, and send the change order to theprocessing component. The display component also includes a displaycomponent change writer configured to send the first change to theprocessing component. The display component further includes a displaycomponent change reader configured to receive changes. The displaycomponent map manager may also be configured to generate a pre-changestate. The display component map manager may include a change buffer.

In one or more embodiments, the processing component includes aprocessing component map manager configured to receive the change orderand apply changes based on the change order. The processing componentalso includes a processing component change writer configured to sendthe second change to the display component. The processing componentfurther includes a processing component change reader configured toreceive changes. The processing component map manager may also beconfigured to generate a pre-change state. The processing component mapmanager may include a change buffer. The processing component mayinclude removable media for data storage.

In still another embodiment, a computer implemented method for updatinga point map on a system having a head-mounted audio-visual displaycomponent, and a torso-mounted processing component communicativelycoupled to the display component includes the processing componentdividing the point map into a plurality of point map subunits. Themethod also includes the processing component sending a first subset ofthe plurality of point map subunits to the display component. The methodfurther includes the processing component sending a second subset of theplurality of point map subunits to the display component in response tomovement of the display component.

In one or more embodiments, the method also includes the displaycomponent storing the first subset of the plurality of point mapsubunits, the display component detecting a movement thereof, and thedisplay component sending movement data to the processing component, Themethod further includes the display component deleting a portion of thefirst subset of the plurality of point map subunits based on themovement, the display component receiving the second subset of theplurality of point map subunits, and the display component storing thesecond subset of the plurality of point map subunits. The portion of thefirst subset of the plurality of point map subunits and the secondsubset of the plurality of point map subunits may have substantially thesame size.

In one or more embodiments, the second subset of the plurality of pointmap subunits corresponds to a direction of the movement, and the portionof the first subset of the plurality of point map subunits correspondsto a second direction opposite to the direction of the movement. Theplurality of point map subunits may be a 3D array. The 3D array may be a3×3×1 array, a 10×10×1 array, or a 6×6×3 array.

In yet another embodiment, a mixed reality system includes ahead-mounted audio-visual display component, and a torso-mountedprocessing component communicatively coupled to the display component.The processing component is configured to divide a point map into aplurality of point map subunits, send a first subset of the plurality ofpoint map subunits to the display component, and send a second subset ofthe plurality of point map subunits to the display component in responseto movement of the display component. The display component isconfigured to store the first subset of the plurality of point mapsubunits, detect a movement thereof, send movement data to theprocessing component, delete a portion of the first subset of theplurality of point map subunits based on the movement, receive thesecond subset of the plurality of point map subunits, and storing thesecond subset of the plurality of point map subunits.

In one or more embodiments, the portion of the first subset of theplurality of point map subunits and the second subset of the pluralityof point map subunits have substantially the same size. The secondsubset of the plurality of point map subunits may corresponds to adirection of the movement, and the portion of the first subset of theplurality of point map subunits may correspond to a second directionopposite to the direction of the movement. The plurality of point mapsubunits may be a 3D array. The 3D array may be a 3×3×1 array, a 10×10×1array, or a 6×6×3 array.

In another embodiment, a system for communicating data across a USBcable includes a writer, a reader, and a data structure including anarray of cells. Each cell of the array includes an owner indicator, astate indicator, and cell data.

In one or more embodiments, the array of cells includes a plurality ofmap cells, and at least one transition cell. The system may also includea cell list including a plurality of pointers corresponding to each cellof a map, and a count of the pointers or cells of the map.

In still another embodiment, a method for communicating data across aUSB cable using a system including a writer, a reader, and a datastructure including an array of cells, each cell of the array includingan owner indicator, a state indicator, and cell data, includesinitializing the data structure by setting all owner indicators to“owner none” and setting all state indicators to “invalid”. The methodalso includes identifying a cell to be transferred across the USB cable.The method further includes setting the owner indicator of the cell to“comm2”. Moreover, the method includes setting the state indicator ofthe cell to “USB”. In addition, the method includes transferring thecell across the USB cable. The method also includes setting the ownerindicator of the cell to “map” after transferring the cell across theUSB cable. The method further includes setting the state indicator ofthe cell to “map” after transferring the cell across the USB cable.

In one or more embodiments, the method also includes the system readinga cell list including a plurality of pointers corresponding to each cellhaving an owner indicator set to “map”, and a count of pointers of theplurality or cells having an owner indicator set to “map”. The methodmay also include the writing populating a request array. The method mayfurther include invalidating the cell by setting the owner indicator ofthe cell to “owner none” and setting the state indicator of the cell to“invalid”. Moreover, the method may include sending the cell by settingthe owner indicator of the cell to “comm2” and setting the stateindicator of the cell to “USB”.

Additional and other objects, features, and advantages of the disclosureare described in the detail description, figures and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the design and utility of various embodiments ofthe present disclosure. It should be noted that the figures are notdrawn to scale and that elements of similar structures or functions arerepresented by like reference numerals throughout the figures. In orderto better appreciate how to obtain the above-recited and otheradvantages and objects of various embodiments of the disclosure, a moredetailed description of the present disclosures briefly described abovewill be rendered by reference to specific embodiments thereof, which areillustrated in the accompanying drawings. Understanding that thesedrawings depict only typical embodiments of the disclosure and are nottherefore to be considered limiting of its scope, the disclosure will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings in which:

FIGS. 1-4 schematically depict VR/AR/MR systems and subsystems thereof,according to some embodiments.

FIG. 5 depicts the focal planes of a VR/AR/MR system, according to someembodiments.

FIG. 6 depicts a simplified view of a passable world model, according tosome embodiments.

FIG. 7 depicts a method of rendering using a passable world model,according to some embodiments.

FIG. 8 depicts a topological map according to some embodiments.

FIG. 9 depicts a high level flow diagram for a process of localizationusing a topological map, according to some embodiments.

FIG. 10 depicts a geometric map as a connection between variouskeyframes, according to some embodiments.

FIG. 11 depicts a topological map layered on top of a geometric map,according some embodiments.

FIG. 12 depicts a high level flow diagram for a process of performing awave propagation bundle adjustment, according to some embodiments.

FIG. 13 depicts map points, keyframes, and render lines from the mappoints to the keyframes as seen through a virtual keyframe, according tosome embodiments.

FIG. 14 depicts a high level flow diagram for a process of finding mappoints based on render rather than search, according to someembodiments.

FIG. 15 schematically depicts a mapping system includes a plurality ofAR/MR systems, according to some embodiments.

FIG. 16 depicts a workflow for an asynchronous mapping method using amulticomponent mapping system, according to some embodiments.

FIGS. 17A-17D depict a plurality of exemplary loop closure operations,according to some embodiments.

FIG. 18 depicts a workflow for an asynchronous mapping method using amulticomponent mapping system with map management, according to someembodiments.

FIG. 19 schematically depicts an AR/MR system for mapping and mapsynchronization, according to some embodiments.

FIG. 20 schematically depicts a wearable map manager of an AR/MR systemfor mapping and map synchronization generating a change order, accordingto some embodiments.

FIG. 21 schematically depicts a power pack map manager of an AR/MRsystem for mapping and map synchronization applying a plurality ofreceived state changes based on a change order, according to someembodiments.

FIG. 22 schematically depicts a wearable map manager of an AR/MR systemfor mapping and map synchronization processing a plurality of receivedstate changes and generating a change order, according to someembodiments.

FIG. 23 schematically depicts a power pack map manager of an AR/MRsystem for mapping and map synchronization processing a plurality ofreceived state changes based on a change order, according to someembodiments.

FIGS. 24 and 25 schematically depict a cell streaming method in amultiple component mapping system, according to some embodiments.

FIGS. 26 and 27 depict a data structure for zero copy data transfer,according to some embodiments.

FIG. 28 is a block diagram schematically depicting an illustrativecomputing system, according to some embodiments.

DETAILED DESCRIPTION

Various embodiments of the disclosure are directed to systems, methods,and articles of manufacture for mapping and map synchronization inmultiple component systems in a single embodiment or in multipleembodiments. Other objects, features, and advantages of the disclosureare described in the detailed description, figures, and claims.

Various embodiments will now be described in detail with reference tothe drawings, which are provided as illustrative examples of thedisclosure so as to enable those skilled in the art to practice thedisclosure. Notably, the figures and the examples below are not meant tolimit the scope of the present disclosure. Where certain elements of thepresent disclosure may be partially or fully implemented using knowncomponents (or methods or processes), only those portions of such knowncomponents (or methods or processes) that are necessary for anunderstanding of the present disclosure will be described, and thedetailed descriptions of other portions of such known components (ormethods or processes) will be omitted so as not to obscure thedisclosure. Further, various embodiments encompass present and futureknown equivalents to the components referred to herein by way ofillustration.

The head mounted audio-visual display system and user physical contactmodulating between systems may be implemented independently of AR/MRsystems, but some embodiments below are described in relation to AR/MRsystems for illustrative purposes only. The contact modulating systemsdescribed herein may also be used in an identical manner with VRsystems.

Summary of Problems and Solutions

Mapping is fundamental to many AR/MR system functions, and mapsynchronization across components of multiple component AR/MR systemsfacilitates stable mapping for a coherent and consistent AR/MR scenario.System limitations such as processing power, memory, bandwidth, datasources, component latency, and multiple operating systems, processorsand architectures can result in overall system latency during mapping,which can negatively impact AR/MR system performance.

For example, in some wearables, tracking consumes a sizable portion ofthe map data and related processing, and mapping generates most of themap data produced on the wearable. Further, some wearables front facing(“FOV”) camera that provide data for mapping. Accordingly, it ispreferable to run latency critical jobs and jobs that use FOV cameradata on the wearable. However, wearables have limited memory andprocessing budget/power. For instance, many wearable cannot store theentire sparse point map for a large real world area/space. Also, manywearables cannot run large geometric optimizations (e.g., global bundleadjustment, loop closure, etc.) in a practical amount of time.

Power packs typically have more memory (including some persistentmemory, such as SD cards) and processing power than the wearable.Accordingly, power packs have access to more map data (including sparsepoint map data for large real world areas and dense point map data forlimited real world areas) and the processing power to run largegeometric optimizations (e.g., global bundle adjustment, loop closure,etc.) Power pack may even have sufficient processing power to runoptimizations involving dense point map data. However, map data maytravel from the wearable to the power pack through a link (e.g., USB)and updated maps may travel from the power pack to the wearable throughthe link. Links, such as USB, may have limited bandwidth that results inunacceptable system latency. For instance, it is preferable for latencysensitive jobs (e.g., head pose related jobs) to be performed at thewearable without processing at the power pack.

Some AR/MR systems also include a cloud based storage and processingcomponent. Cloud components may have access to large amounts ofpersistent storage and processing power. Cloud component may also haveaccess to sparse and dense point maps of the same real worldarea/environment produced by different systems or the same system at anearlier time. Data from different systems may be stored as a mesh ofmaps on the cloud allowing for larger scale optimization. Accordingly,cloud components can perform processing intensive optimizations thatinvolve sparse and dense point map date from multiple sessions. However,network connections between cloud components and power packs andwearables are not always available. Accordingly, it is preferable forlatency sensitive jobs (e.g., head pose related jobs) to be performedwith involvement of cloud components. In some embodiments, a fourthlayer of mapping can exists on top of the cloud component layer.

Further, these AR/MR system components involve different platforms,architectures, and organization structures. For instance, these systemcomponents (wearable, power pack, cloud) can have different processorarchitectures, memory hierarchy, and storage models (e.g.,Myriad/Streaming Hybrid Architecture Vector Engine (“SHAVE”) forwearable, NVidia/ARM for power pack, PC for cloud). The systemcomponents can also have different framework environments/operatingsystems (e.g., minotaur for wearable, malleus for power pack, variousOSs for cloud). Further, the system components can have differentcodebases, release processes, etc. (e.g., in particular between wearableand power pack vs cloud). These component differences can furthercomplicate map synchronization.

The embodiments described herein include a map data processing pipelinethat allows parallel processing for all system components by formattingprocessing results as changes and utilizing change orders. Thisprocessing pipeline reduces system latency and allows system componentsto perform best matched jobs while minimizing system component downtimewhile waiting for serial processing of map data. The embodiments alsoinclude a map data format/structure including independently transferableand manipulable map subunits. This map data format/structure allows thewearable to operate on a subset of the map subunits while the power packstores the plurality of map subunits defining a sparse point map of areal world area. The embodiments further include a data format/structurefor transferring data across a bandwidth limited channel includingownership and state information. This map data format/structure allowsmore efficient data transfers across such bandwidth limited channels(e.g., USB).

Illustrative VR, AR, and/or MR System

The description that follows pertains to an illustrative VR, AR, and/orMR system with which the contact modulating system may be practiced.However, it is to be understood that the embodiments also lendsthemselves to applications in other types of display systems (includingother types of VR, AR, and/or MR systems), and therefore the embodimentsare not to be limited to only the illustrative system disclosed herein.

Various components of VR, AR, and/or MR virtual image systems 100 aredepicted in FIGS. 1 to 4 . The virtual image generation system 100comprises a frame structure 102 worn by an end user 50, a displaysubsystem 110 carried by the frame structure 102, such that the displaysubsystem 110 is positioned in front of the eyes of the end user 50, anda speaker 106 carried by the frame structure 102, such that the speaker106 is positioned adjacent the ear canal of the end user 50 (optionally,another speaker (not shown) is positioned adjacent the other ear canalof the end user 50 to provide for stereo/shapeable sound control). Thedisplay subsystem 110 is designed to present the eyes of the end user 50with light patterns that can be comfortably perceived as augmentationsto physical reality, with high-levels of image quality andthree-dimensional perception, as well as being capable of presentingtwo-dimensional content. The display subsystem 110 presents a sequenceof frames at high frequency that provides the perception of a singlecoherent scene.

In the illustrated embodiments, the display subsystem 110 employs“optical see-through” display through which the user can directly viewlight from real objects via transparent (or semi-transparent) elements.The transparent element, often referred to as a “combiner,” superimposeslight from the display over the user's view of the real world. To thisend, the display subsystem 110 comprises a partially transparentdisplay. The display is positioned in the end user's 50 field of viewbetween the eyes of the end user 50 and an ambient environment, suchthat direct light from the ambient environment is transmitted throughthe display to the eyes of the end user 50.

In the illustrated embodiments, an image projection assembly provideslight to the partially transparent display, thereby combining with thedirect light from the ambient environment, and being transmitted fromthe display to the eyes of the user 50. The projection subsystem may bean optical fiber scan-based projection device, and the display may be awaveguide-based display into which the scanned light from the projectionsubsystem is injected to produce, e.g., images at a single opticalviewing distance closer than infinity (e.g., arm's length), images atmultiple, discrete optical viewing distances or focal planes, and/orimage layers stacked at multiple viewing distances or focal planes torepresent volumetric 3D objects. These layers in the light field may bestacked closely enough together to appear continuous to the human visualsubsystem (i.e., one layer is within the cone of confusion of anadjacent layer). Additionally or alternatively, picture elements may beblended across two or more layers to increase perceived continuity oftransition between layers in the light field, even if those layers aremore sparsely stacked (i.e., one layer is outside the cone of confusionof an adjacent layer). The display subsystem 110 may be monocular orbinocular.

The virtual image generation system 100 may also include one or moresensors (not shown) mounted to the frame structure 102 for detecting theposition and movement of the head 54 of the end user 50 and/or the eyeposition and inter-ocular distance of the end user 50. Such sensors mayinclude image capture devices (such as cameras), microphones, inertialmeasurement units, accelerometers, compasses, GPS units, radio devices,and/or gyros). Many of these sensors operate on the assumption that theframe 102 on which they are affixed is in turn substantially fixed tothe user's head, eyes, and ears.

The virtual image generation system 100 may also include a userorientation detection module. The user orientation module detects theinstantaneous position of the head 54 of the end user 50 (e.g., viasensors coupled to the frame 102) and may predict the position of thehead 54 of the end user 50 based on position data received from thesensors. Detecting the instantaneous position of the head 54 of the enduser 50 facilitates determination of the specific actual object that theend user 50 is looking at, thereby providing an indication of thespecific virtual object to be generated in relation to that actualobject and further providing an indication of the position in which thevirtual object is to be displayed. The user orientation module may alsotrack the eyes of the end user 50 based on the tracking data receivedfrom the sensors.

The virtual image generation system 100 may also include a controlsubsystem that may take any of a large variety of forms. The controlsubsystem includes a number of controllers, for instance one or moremicrocontrollers, microprocessors or central processing units (CPUs),digital signal processors, graphics processing units (GPUs), otherintegrated circuit controllers, such as application specific integratedcircuits (ASICs), programmable gate arrays (PGAs), for instance fieldPGAs (FPGAs), and/or programmable logic controllers (PLUs).

The control subsystem of virtual image generation system 100 may includea central processing unit (CPU), a graphics processing unit (GPU), oneor more frame buffers, and a three-dimensional data base for storingthree-dimensional scene data. The CPU may control overall operation,while the GPU may render frames (i.e., translating a three-dimensionalscene into a two-dimensional image) from the three-dimensional datastored in the three-dimensional data base and store these frames in theframe buffers. One or more additional integrated circuits may controlthe reading into and/or reading out of frames from the frame buffers andoperation of the image projection assembly of the display subsystem 110.

The various processing components of the virtual image generation system100 may be physically contained in a distributed subsystem. For example,as illustrated in FIGS. 1 to 4 , the virtual image generation system 100may include a local processing and data module 130 operatively coupled,such as by a wired lead or wireless connectivity 136, to the displaysubsystem 110 and sensors. The local processing and data module 130 maybe mounted in a variety of configurations, such as fixedly attached tothe frame structure 102 (FIG. 1 ), fixedly attached to a helmet or hat56 (FIG. 2 ), removably attached to the torso 58 of the end user 50(FIG. 3 ), or removably attached to the hip 60 of the end user 50 in abelt-coupling style configuration (FIG. 4 ). The virtual imagegeneration system 100 may also include a remote processing module 132and remote data repository 134 operatively coupled, such as by a wiredlead or wireless connectivity 138, 140, to the local processing and datamodule 130, such that these remote modules 132, 134 are operativelycoupled to each other and available as resources to the local processingand data module 130.

The local processing and data module 130 may comprise a power-efficientprocessor or controller, as well as digital memory, such as flashmemory, both of which may be utilized to assist in the processing,caching, and storage of data captured from the sensors and/or acquiredand/or processed using the remote processing module 132 and/or remotedata repository 134, possibly for passage to the display subsystem 110after such processing or retrieval. The remote processing module 132 maycomprise one or more relatively powerful processors or controllersconfigured to analyze and process data and/or image information. Theremote data repository 134 may comprise a relatively large-scale digitaldata storage facility, which may be available through the internet orother networking configuration in a “cloud” resource configuration. Insome embodiments, all data is stored and all computation is performed inthe local processing and data module 130, allowing fully autonomous usefrom any remote modules.

The couplings 136, 138, 140 between the various components describedabove may include one or more wired interfaces or ports for providingwires or optical communications, or one or more wireless interfaces orports, such as via RF, microwave, and IR for providing wirelesscommunications. In some implementations, all communications may bewired, while in other implementations all communications may bewireless. In still further implementations, the choice of wired andwireless communications may be different from that illustrated in FIGS.1 to 4 . Thus, the particular choice of wired or wireless communicationsshould not be considered limiting.

In some embodiments, the user orientation module is contained in thelocal processing and data module 130, while CPU and GPU are contained inthe remote processing module. In alternative embodiments, the CPU, GPU,or portions thereof may be contained in the local processing and datamodule 130. The 3D database can be associated with the remote datarepository 134 or disposed locally.

Some VR, AR, and/or MR systems use a plurality of volume phaseholograms, surface-relief holograms, or light guiding optical elementsthat are embedded with depth plane information to generate images thatappear to originate from respective depth planes. In other words, adiffraction pattern, or diffractive optical element (“DOE”) may beembedded within or imprinted/embossed upon a light guiding opticalelement (“LOE”; e.g., a planar waveguide) such that as collimated light(light beams with substantially planar wavefronts) is substantiallytotally internally reflected along the LOE, it intersects thediffraction pattern at multiple locations and exits toward the user'seye. The DOEs are configured so that light exiting therethrough from anLOE are verged so that they appear to originate from a particular depthplane. The collimated light may be generated using an optical condensinglens (a “condenser”).

For example, a first LOE may be configured to deliver collimated lightto the eye that appears to originate from the optical infinity depthplane (0 diopters). Another LOE may be configured to deliver collimatedlight that appears to originate from a distance of 2 meters (½ diopter).Yet another LOE may be configured to deliver collimated light thatappears to originate from a distance of 1 meter (1 diopter). By using astacked LOE assembly, it can be appreciated that multiple depth planesmay be created, with each LOE configured to display images that appearto originate from a particular depth plane. It should be appreciatedthat the stack may include any number of LOEs. However, at least Nstacked LOEs are required to generate N depth planes. Further, N, 2N or3N stacked LOEs may be used to generate RGB colored images at N depthplanes.

In order to present 3-D virtual content to the user, the VR, AR, and/orMR system projects images of the virtual content into the user's eye sothat they appear to originate from various depth planes in the Zdirection (i.e., orthogonally away from the user's eye). In other words,the virtual content may not only change in the X and Y directions (i.e.,in a 2D plane orthogonal to a central visual axis of the user's eye),but it may also appear to change in the Z direction such that the usermay perceive an object to be very close or at an infinite distance orany distance in between. In other embodiments, the user may perceivemultiple objects simultaneously at different depth planes. For example,the user may see a virtual dragon appear from infinity and run towardsthe user. Alternatively, the user may simultaneously see a virtual birdat a distance of 3 meters away from the user and a virtual coffee cup atarm's length (about 1 meter) from the user.

Multiple-plane focus systems create a perception of variable depth byprojecting images on some or all of a plurality of depth planes locatedat respective fixed distances in the Z direction from the user's eye.Referring now to FIG. 5 , it should be appreciated that multiple-planefocus systems may display frames at fixed depth planes 150 (e.g., thesix depth planes 150 shown in FIG. 5 ). Although MR systems can includeany number of depth planes 150, one exemplary multiple-plane focussystem has six fixed depth planes 150 in the Z direction. In generatingvirtual content one or more of the six depth planes 150, 3-D perceptionis created such that the user perceives one or more virtual objects atvarying distances from the user's eye. Given that the human eye is moresensitive to objects that are closer in distance than objects thatappear to be far away, more depth planes 150 are generated closer to theeye, as shown in FIG. 5 . In other embodiments, the depth planes 150 maybe placed at equal distances away from each other.

Depth plane positions 150 may be measured in diopters, which is a unitof optical power equal to the inverse of the focal length measured inmeters. For example, in some embodiments, depth plane 1 may be ⅓diopters away, depth plane 2 may be 0.3 diopters away, depth plane 3 maybe 0.2 diopters away, depth plane 4 may be 0.15 diopters away, depthplane 5 may be 0.1 diopters away, and depth plane 6 may representinfinity (i.e., 0 diopters away). It should be appreciated that otherembodiments may generate depth planes 150 at other distances/diopters.Thus, in generating virtual content at strategically placed depth planes150, the user is able to perceive virtual objects in three dimensions.For example, the user may perceive a first virtual object as being closeto him when displayed in depth plane 1, while another virtual objectappears at infinity at depth plane 6. Alternatively, the virtual objectmay first be displayed at depth plane 6, then depth plane 5, and so onuntil the virtual object appears very close to the user. It should beappreciated that the above examples are significantly simplified forillustrative purposes. In another embodiment, all six depth planes maybe concentrated on a particular focal distance away from the user. Forexample, if the virtual content to be displayed is a coffee cup half ameter away from the user, all six depth planes could be generated atvarious cross-sections of the coffee cup, giving the user a highlygranulated 3-D view of the coffee cup.

In some embodiments, the VR, AR, and/or MR system may work as amultiple-plane focus system. In other words, all six LOEs may beilluminated simultaneously, such that images appearing to originate fromsix fixed depth planes are generated in rapid succession with the lightsources rapidly conveying image information to LOE 1, then LOE 2, thenLOE 3 and so on. For example, a portion of the desired image, comprisingan image of the sky at optical infinity may be injected at time 1 andthe LOE retaining collimation of light (e.g., depth plane 6 from FIG. 5) may be utilized. Then an image of a closer tree branch may be injectedat time 2 and an LOE configured to create an image appearing tooriginate from a depth plane 10 meters away (e.g., depth plane 5 fromFIG. 5 ) may be utilized; then an image of a pen may be injected at time3 and an LOE configured to create an image appearing to originate from adepth plane 1 meter away may be utilized. This type of paradigm can berepeated in rapid time sequential (e.g., at 360 Hz) fashion such thatthe user's eye and brain (e.g., visual cortex) perceives the input to beall part of the same image.

VR, AR, and/or MR systems may project images (i.e., by diverging orconverging light beams) that appear to originate from various locationsalong the Z axis (i.e., depth planes) to generate images for a 3-Dexperience/scenario. As used in this application, light beams include,but are not limited to, directional projections of light energy(including visible and invisible light energy) radiating from a lightsource. Generating images that appear to originate from various depthplanes conforms the vergence and accommodation of the user's eye forthat image, and minimizes or eliminates vergence-accommodation conflict.

Exemplary Passable World Models

FIG. 6 illustrates the components of a passable world model 2000according to some embodiments. As a user 2001 walks through anenvironment, the user's individual AR system 2010 captures information(e.g., images, location information, position and orientationinformation, etc.) and saves the information through posed taggedimages. In the illustrated embodiment, an image may be taken of theobject 2020 (which resembles a table) and map points 2004 may becollected based on the captured image. This forms the core of thepassable world model, as shown by multiple keyframes (e.g., cameras)2002 that have captured information about the environment.

As shown in FIG. 6 , there may be multiple keyframes 2002 that captureinformation about a space at any given point in time. For example, akeyframe may be another user's AR system capturing information from aparticular point of view. Another keyframe may be a room-basedcamera/sensor system that is capturing images and points 2004 through astationary point of view. By triangulating images and points frommultiple points of view, the position and orientation of real objects ina 3D space may be determined.

In some embodiments, the passable world model 2008 is a combination ofraster imagery, point and descriptors clouds, and polygonal/geometricdefinitions (referred to herein as parametric geometry). All thisinformation is uploaded to and retrieved from the cloud, a section ofwhich corresponds to a particular space that the user may have walkedinto. As shown in FIG. 6 , the passable world model also contains manyobject recognizers 2012 that work on the cloud or on the user'sindividual system 2010 to recognize objects in the environment based onpoints and pose-tagged images captured through the various keyframes ofmultiple users. Essentially by continually capturing information aboutthe physical world through multiple keyframes 2002, the passable worldis always growing, and may be consulted (continuously or as needed) inorder to determine how to render virtual content in relation to existingphysical objects of the real world. By collecting information from theuser's environment, a piece of the passable world 2006 isconstructed/augmented, and may be “passed” along to one or more AR userssimultaneously or in the future.

Asynchronous communications is established between the user's respectiveindividual AR system and the cloud based computers (e.g., servercomputers). In other words, the user's individual AR system isconstantly updating information about the user's surroundings to thecloud, and also receiving information from the cloud about the passableworld. Thus, rather than each AR user having to capture images andrecognize objects based on the captured images, having an asynchronoussystem allows the system to be more efficient. Information that alreadyexists about that part of the world is automatically communicated to theindividual AR system while new information is updated to the cloud. Itshould be appreciated that the passable world model lives both on thecloud or other form of networking computing or peer to peer system, andalso may live on the user's individual AR system.

In some embodiments, the AR system may employ different levels ofresolutions for the local components (e.g., computational component 130such as a power pack) and remote components (e.g., cloud based computers132). This is because the remote components (e.g., resources that resideon the cloud servers) are typically more computationally powerful thanlocal components. The cloud based computers may pick data collected bythe many different individual AR systems, and/or one or more space orroom based sensor systems, and utilize this information to add on to thepassable world model. The cloud based computers may aggregate only thebest (e.g., most useful) information into a persistent world model. Inother words, redundant information and/or less-than-optimal qualityinformation may be timely disposed so as not to deteriorate the qualityand/or performance of the system.

FIG. 10 illustrates an example method 2100 of interacting with thepassable world model according to some embodiments. At 2102, the user'sindividual AR system may detect a location and orientation of the userwithin the world. In some embodiments, the location may be derived by atopological map of the system, as will be described in further detailbelow. In some embodiments, the location may be derived by GPS or anyother localization tool. It should be appreciated that the passableworld may be constantly accessed by the individual AR system.

In another embodiment (not shown), the user may request access toanother user's space, prompting the system to access that section of thepassable world, and associated parametric information corresponding tothe other user. Thus, there may be many triggers for the passable world.At the simplest level, however, it should be appreciated that thepassable world is constantly being updated and accessed by multiple usersystems, thereby constantly adding and receiving information from thecloud.

Following the above example, based on the known location of the user, at2104, the system may draw a radius denoting a physical area around theuser that communicates both the position and intended direction of theuser. Next, at 2106, the system may retrieve a piece of the passableworld based on the anticipated position of the user. In someembodiments, the piece of the passable world may contain informationfrom the geometric map of the space acquired through previous keyframesand captured images and data stored in the cloud. At 2108, the AR systemuploads information from the user's environment into the passable worldmodel. At 2110, based on the uploaded information, the AR system rendersthe passable world associated with the position of the user to theuser's individual AR system.

This information enables virtual content to meaningfully interact withthe user's real surroundings in a coherent manner. For example, avirtual “monster” may be rendered to be originating from a particularbuilding of the real world. Or, in another example, a user may leave avirtual object in relation to physical coordinates of the real worldsuch that a friend (also wearing the AR system) finds the virtual objectin the same physical coordinates. In order to enable such capabilities(and many more), it is important for the AR system to constantly accessthe passable world to retrieve and upload information. It should beappreciated that the passable world contains persistent digitalrepresentations of real spaces that is crucially utilized in renderingvirtual and/or digital content in relation to real coordinates of aphysical space. It should be appreciated that the AR system may maintaincoordinates of the real world and/or virtual world. In some embodiments,a third party may maintain the map (e.g., coordinates) of the realworld, and the AR system may consult the map to determine one or moreparameters in order to render virtual content in relation to realobjects of the world.

It should be appreciated that the passable world model does not itselfrender content that is displayed to the user. Rather it is a high levelconcept of dynamically retrieving and updating a persistent digitalrepresentation of the real world in the cloud. In some embodiments, thederived geometric information is loaded onto a game engine, which thenrenders content associated with the passable world. Thus, regardless ofwhether the user is in a particular space or not, that particular spacehas a digital representation in the cloud that can be accessed by anyuser. This piece of the passable world may contain information about thephysical geometry of the space and imagery of the space, informationabout various avatars that are occupying the space, information aboutvirtual objects and other miscellaneous information.

As described in detail further herein, one or more object recognizersmay examine or “crawl” the passable world models, tagging points thatbelong to parametric geometry. Parametric geometry, points anddescriptors may be packaged into passable world models, to allow lowlatency passing or communicating of information corresponding to aportion of a physical world or environment. In some embodiments, the ARsystem can implement a two tier structure, in which the passable worldmodel allow fast pose processing in a first tier, but then inside thatframework is a second tier (e.g., FAST features). In some embodiments,the second tier structure can increase resolution by performing aframe-to-frame based three-dimensional (3D) feature mapping.

Topological Maps

An integral part of the passable world model is to create maps of veryminute areas of the real world. For example, in order to render virtualcontent in relation to physical objects, very detailed localization isrequired. Such localization may not be achieved simply through GPS ortraditional location detection techniques. For example, the AR systemmay not only require coordinates of a physical location that a user isin, but may, for example, need to know exactly what room of a buildingthe user is located in. Based on this information, the AR system mayretrieve data (e.g., specific geometries of real objects in the room,map points for the room, geometric information of the room, etc.) forthat room to appropriately display virtual content in relation to thereal objects of the identified room. At the same time, however, thisprecise, granular localization must be done in a cost-effective mannersuch that not too many resources are consumed unnecessarily.

To this end, the AR system may use topological maps for localizationpurposes instead of GPS or retrieving detailed geometric maps createdfrom extracted points and pose tagged images (e.g., the geometric pointsmay be too specific, and hence most costly). In some embodiments, thetopological map is a simplified representation of physical spaces in thereal world that is easily accessible from the cloud and only presents afingerprint of a space, and the relationship between various spaces.Further details about the topological map will be provided furtherbelow.

In some embodiments, the AR system may layer topological maps on thepassable world model, for example to localize nodes. The topological mapcan layer various types of information on the passable world model, forinstance: point cloud, images, objects in space, global positioningsystem (GPS) data, Wi-Fi data, histograms (e.g., color histograms of aroom), received signal strength (RSS) data, etc. This allows variouslayers of information (e.g., a more detailed layer of information tointeract with a more high-level layer) to be placed in context with eachother, such that it can be easily retrieved. This information may bethought of as fingerprint data; in other words, it is designed to bespecific enough to be unique to a location (e.g., a particular room).

As discussed above, in order to create a complete virtual world that canbe reliably passed between various users, the AR system capturesdifferent types of information about the user's surroundings (e.g., mappoints, features, pose tagged images, objects in a scene, etc.). Thisinformation is processed and stored in the cloud such that it can beretrieved as needed. As mentioned previously, the passable world modelis a combination of raster imagery, point and descriptors clouds, andpolygonal/geometric definitions (referred to herein as parametricgeometry). Thus, it should be appreciated that the sheer amount ofinformation captured through the users' individual AR system allows forhigh quality and accuracy in creating the virtual world.

In other words, since the various AR systems (e.g., user-specifichead-mounted systems, room-based sensor systems, etc.) are constantlycapturing data corresponding to the immediate environment of therespective AR system, very detailed and accurate information about thereal world in any point in time may be known with a high degree ofcertainty. Although this amount of information is highly useful for ahost of AR applications, for localization purposes, sorting through thatmuch information to find the piece of passable world most relevant tothe user is highly inefficient and costs precious bandwidth.

To this end, the AR system creates a topological map that essentiallyprovides less granular information about a particular scene or aparticular place. In some embodiments, the topological map may bederived through global positioning system (GPS) data, Wi-Fi data,histograms (e.g., color histograms of a room), received signal strength(RSS) data, etc. For example, the topological map may be created byhistograms (e.g., a color histogram) of various rooms/areas/spaces, andbe reduced to a node on the topological map. For example, when a userwalks into a room or space, the AR system may take a single image (orother information) and construct a color histogram of the image. Itshould be appreciated that on some level, the histogram of a particularspace will be mostly constant over time (e.g., the color of the walls,the color of objects of the room, etc.). In other words, each room orspace has a distinct signature that is different from any other room orplace. This unique histogram may be compared to other histograms ofother spaces/areas and identified. Now that the AR system knows whatroom the user is in, the remaining granular information may be easilyaccessed and downloaded.

Thus, although the histogram will not contain particular informationabout all the features and points that have been captured by variouscameras (keyframes), the system may immediately detect, based on thehistogram, where the user is, and then retrieve all the more particulargeometric information associated with that particular room or place. Inother words, rather than sorting through the vast amount of geometricand parametric information that encompasses that passable world model,the topological map allows for a quick and efficient way to localize theAR user. Based on the localization, the AR system retrieves thekeyframes and points that are most relevant to the identified location.For example, after the system has determined that the user is in aconference room of a building, the system may then retrieve all thekeyframes and points associated with the conference room rather thansearching through all the geometric information stored in the cloud.

Referring now to FIG. 8 , an example embodiment of a topological map4300 is presented. As discussed above, the topological map 4300 may be acollection of nodes 4302 and connections 4304 between the nodes 4302(e.g., represented by connecting lines). Each node 4302 represents aparticular location (e.g., the conference room of an office building)having a distinct signature or fingerprint (e.g., GPS information, colorhistogram or other histogram, Wi-Fi data, RSS data etc.) and the linesmay represent the connectivity between them. It should be appreciatedthat the connectivity may not have anything to do with geographicalconnectivity, but rather may simply be a shared device or a shared user.For example, a first user may have walked from a first node to a secondnode. This relationship may be represented through a connection betweenthe nodes. As the number of AR users increases, the nodes andconnections between the nodes will also proportionally increase,providing more precise information about various locations.

Once the AR system has identified a node of the topological map, thesystem may then retrieve a set of geometric information pertaining tothe node to determine how/where to display virtual content in relationto the real objects of that space. Thus, layering the topological map onthe geometric map is especially helpful for localization and efficientlyretrieving only relevant information from the cloud.

In some embodiments, the AR system can represent two images captured byrespective cameras of a part of the same scene in a graph theoreticcontext as first and second pose tagged images. It should be appreciatedthat the cameras in this context may refer to a single camera takingimages of different scenes, or it may be two different cameras. There issome strength of connection between the pose tagged images, which could,for example, be the points that are in the field of views of both of thecameras. In some embodiments, the cloud based computer may constructsuch as a graph (e.g., a topological representation of a geometric worldsimilar to that of FIG. 8 ). The total number of nodes and edges in thegraph is much smaller than the total number of points in the images.

At a higher level of abstraction, other information monitored by the ARsystem can be hashed together. For example, the cloud based computer(s)may hash together one or more of global positioning system (GPS)location information, Wi-Fi location information (e.g., signalstrengths), color histograms of a physical space, and/or informationabout physical objects around a user. The more points of data there are,the more likely that the computer will statistically have a uniqueidentifier for that space. In this case, space is a statisticallydefined concept.

As an example, an office may be a space that is represented as, forexample a large number of points and two dozen pose tagged images. Thesame space may be represented topologically as a graph having only acertain number of nodes (e.g., 5, 25, 100, 1000, etc.), which can beeasily hashed against. Graph theory allows representation ofconnectedness, for example as a shortest path algorithmically betweentwo spaces.

Thus, the system abstracts away from the specific geometry by turningthe geometry into pose tagged images having implicit topology. Thesystem takes the abstraction a level higher by adding other pieces ofinformation, for example color histogram profiles, and the Wi-Fi signalstrengths. This makes it easier for the system to identify an actualreal world location of a user without having to understand or processall of the geometry associated with the location.

FIG. 9 illustrates an example method 2400 of constructing a topologicalmap. First, at 2402, the user's individual AR system may capture animage from a first point of view of a particular location (e.g., theuser walks into a room of a building, and an image is captured from thatpoint of view). At 2404, a color histogram may be generated based on thecaptured image. As mentioned before, the system may use any other typeof identifying information, (e.g., Wi-Fi data, RSS information, GPSdata, number of windows, etc.) but the color histogram is used in thisexample for illustrative purposes.

Next, at 2406, the system runs a search to identify the location of theuser by comparing the color histogram to a database of color histogramsstored in the cloud. At 2410, a decision is made to determine whetherthe color histogram matches an existing color histogram stored in thecloud. If the color histogram does not match any color histogram of thedatabase of color histograms, it may then be stored as a node in thetopological made (2414). If the color histogram matches an existingcolor histogram of the database, it is stored as a node in the cloud(2412). If the color histogram matches an existing color histogram inthe database, the location is identified, and the appropriate geometricinformation is provided to the individual AR system.

Continuing with the same example, the user may walk into another room oranother location, where the user's individual AR system takes anotherpicture and generates another color histogram of the other location. Ifthe color histogram is the same as the previous color histogram or anyother color histogram, the AR system identifies the location of theuser. If the color histogram is not the same as a stored histogram,another node is created on the topological map. Additionally, since thefirst node and second node were taken by the same user (or samecamera/same individual user system), the two nodes are connected in thetopological map.

In addition to aiding in localization, the topological map may also beused to improve/fix errors and or missing information in geometric maps.In some embodiments, topological maps may be used to find loop-closurestresses in geometric maps or geometric configurations of a particularplace. As discussed above, for any given location or space, images takenby one or more AR systems (multiple field of view images captured by oneuser's individual AR system or multiple users' AR systems) give rise alarge number of map points of the particular space. For example, asingle room may correspond to thousands of map points captured throughmultiple points of views of various cameras (or one camera moving tovarious positions).

The AR system utilizes map points to recognize objects (through objectrecognizers) as discussed above, and to add to on to the passable worldmodel in order to store a more comprehensive picture of the geometry ofvarious objects of the real world. In some embodiments, map pointsderived from various keyframes may be used to triangulate the pose andorientation of the camera that captured the images. In other words, thecollected map points may be used to estimate the pose (e.g., positionand orientation) of the keyframe (e.g. camera) capturing the image.

It should be appreciated, however, that given the large number of mappoints and keyframes, there are bound to be some errors (e.g., stresses)in this calculation of keyframe position based on the map points. Toaccount for these stresses, the AR system may perform a bundle adjust. Abundle adjust allows for the refinement, or optimization of the mappoints and keyframes to minimize the stresses in the geometric map.

For example, as illustrated in FIG. 10 , an example geometric map ispresented. As shown in FIG. 10 , the geometric map may be a collectionof keyframes 2502 that are all connected to each other. The keyframes2502 may represent a point of view from which various map points arederived for the geometric map. In the illustrated embodiment, each nodeof the geometric map represents a keyframe (e.g., camera), and thevarious keyframes are connected to each other through connecting lines2504.

In the illustrated embodiment, the strength of the connection betweenthe different keyframes is represented by the thickness of theconnecting lines 2504. For example, as shown in FIG. 10 , the connectingline between node 2502 a and 2502 b is depicted as a thicker connectingline 2504 as compared to the connecting line between node 2502 a andnode 2502 f. The connecting line between node 2502 a and node 2502 d isalso depicted to be thickener than the connecting line between 2502 band node 2502 d. In some embodiments, the thickness of the connectinglines represents the number of features or map points shared betweenthem. For example, if a first keyframe and a second keyframe are closetogether, they may share a large number of map points (e.g., node 2502 aand node 2502 b), and may thus be represented with a thicker connectingline. Of course, it should be appreciated that other ways ofrepresenting geometric maps may be similarly used.

For example, the strength of the line may be based on a geographicalproximity between the keyframes, in another embodiment. Thus, as shownin FIG. 10 , each geometric map represents a large number of keyframes2502 and their connection to each other. Now, assuming that a stress isidentified in a particular point of the geometric map, a bundle adjustmay be performed to alleviate the stress by radially pushing the stressout radially out from the identified point of stress 2506. The stress ispushed out radially in waves 2508 (e.g., n=1, n=2, etc.) propagatingfrom the point of stress, as will be described in further detail below.

The following description illustrates an example method of performing awave propagation bundle adjust. It should be appreciated that all theexamples below refer solely to wave propagation bundle adjusts, andother types of bundle adjusts may be similarly used in otherembodiments. First, a particular point of stress is identified. In theillustrated embodiment of FIG. 10 , consider the center (node 2502 a) tobe the identified point of stress. For example, the system may determinethat the stress at a particular point of the geometric map is especiallyhigh (e.g., residual errors, etc.) The stress may be identified based onone of two reasons. One, a maximum residual error may be defined for thegeometric map. If a residual error at a particular point is greater thanthe predefined maximum residual error, a bundle adjust may be initiated.Second, a bundle adjust may be initiated in the case of loop closurestresses, as will be described further below (when a topological mapindicates misalignments of map points).

When a stress is identified, the AR system distributes the error evenly,starting with the point of stress and propagating it radially through anetwork of nodes that surround the particular point of stress. Forexample, in the illustrated embodiment, the bundle adjust may distributethe error to n=1 (one degree of separation from the identified point ofstress, node 2502 a) around the identified point of stress. In theillustrated embodiment, nodes 2502 b-2502 g are all part of the n=1 wavearound the point of stress, node 2502 a.

In some cases, this may be sufficient. In other embodiments, the ARsystem may propagate the stress even further, and push out the stress ton=2 (two degrees of separation from the identified point of stress, node2502 a), or n=3 (three degrees of separation from the identified pointof stress, node 2502 a) such that the stress is radially pushed outfurther and further until the stress is distributed evenly. Thus,performing the bundle adjust is an important way of reducing stress inthe geometric maps. Ideally, the stress is pushed out to n=2 or n=3 forbetter results.

In some embodiments, the waves may be propagated in even smallerincrements. For example, after the wave has been pushed out to n=2around the point of stress, a bundle adjust can be performed in the areabetween n=3 and n=2, and propagated radially. By controlling the waveincrements, this iterative wave propagating bundle adjust process can berun on massive data to reduce stresses on the system. In an optionalembodiment, because each wave is unique, the nodes that have beentouched by the wave (e.g., bundle adjusted) may be colored so that thewave does not re-propagate on an adjusted section of the geometric map.In another embodiment, nodes may be colored so that simultaneous wavesmay propagate/originate from different points in the geometric map.

As mentioned previously, layering the topological map on the geometricmap of keyframes and map points may be especially crucial in findingloop-closure stresses. A loop-closure stress refers to discrepanciesbetween map points captured at different times that should be alignedbut are misaligned. For example, if a user walks around the block andreturns to the same place, map points derived from the position of thefirst keyframe and the map points derived from the position of the lastkeyframe as extrapolated from the collected map points should ideally beidentical. However, given stresses inherent in the calculation of pose(position of keyframes) based on the different map points, there areoften errors and the system does not recognize that the user has comeback to the same position because estimated key points from the firstkey frame are not geometrically aligned with map points derived from thelast keyframe. This may be an example of a loop-closure stress.

To this end, the topological map may be used to find the loop-closurestresses in a geometric map. Referring back to the previous example,using the topological map along with the geometric map allows the ARsystem to recognize the loop-closure stresses in the geometric mapbecause the topological map may indicate that the user has come back tothe starting point (based on the color histogram, for example). Forexample, referring to the layered map 2600 of FIG. 11 , the nodes of thetopological map (e.g., 2604 a and 2604 b) are layered on top of thenodes of the geometric map (e.g., 2602 a-2602 f). As shown in FIG. 11 ,the topological map, when placed on top of the geometric map may suggestthat keyframe B (node 2602 g) is the same as keyframe A (node 2602 a).Based on this, a loop closure stress may be detected, the system detectsthat keyframes A and B should be closer together in the same node, andthe system may then perform a bundle adjust. Thus, having identified theloop-closure stress, the AR system may then perform a bundle adjust onthe identified point of stress, using a bundle adjust technique, such asthe one discussed above.

It should be appreciated that performing the bundle adjust based on thelayering of the topological map and the geometric map ensures that thesystem only retrieves the keyframes on which the bundle adjust needs tobe performed instead of retrieving all the keyframes in the system. Forexample, if the AR system identifies, based on the topological map thatthere is a loop-closure stress, the system may simply retrieve thekeyframes associated with that particular node or nodes of thetopological map, and perform the bundle adjust on only those keyframesrather than all the keyframes of the geometric map. Again, this enablesthe system to be efficient and not retrieve unnecessary information thatmight unnecessarily tax the system.

Referring now to FIG. 12 , an example method 2700 for correctingloop-closure stresses based on the topological map is described. At2702, the system may identify a loop closure stress based on atopological map that is layered on top of a geometric map. Once the loopclosure stress has been identified, at 2704, the system may retrieve theset of keyframes associated with the node of the topological map atwhich the loop closure stress has occurred. After having retrieved thekeyframes of that node of the topological map, the system may, at 2706,initiate a bundle adjust on that point in the geometric map. At 2708,the stress is propagated away from the identified point of stress and isradially distributed in waves, to n=1 (and then n=2, n=3, etc.) similarto the technique shown in FIG. 10 .

Mapping

In mapping out the virtual world, it is important to know all thefeatures and points in the real world to accurately portray virtualobjects in relation to the real world. To this end, as discussed above,map points captured from various head-worn AR systems are constantlyadding to the passable world model by adding in new pictures that conveyinformation about various points and features of the real world. Basedon the points and features, as discussed above, one can also extrapolatethe pose and position of the keyframe (e.g., camera, etc.). While thisallows the AR system to collect a set of features (2D points) and mappoints (3D points), it may also be important to find new features andmap points to render a more accurate version of the passable world.

One way of finding new map points and/or features may be to comparefeatures of one image against another. Each feature may have a label orfeature descriptor attached to it (e.g., color, identifier, etc.).Comparing the labels of features in one picture to another picture maybe one way of uniquely identifying natural features in the environment.For example, if there are two keyframes, each of which captures about500 features, comparing the features of one keyframe with the other mayhelp determine new map points. However, while this might be a feasiblesolution when there are just two keyframes, it becomes a very largesearch problem that takes up a lot of processing power when there aremultiple keyframes, each of which captures millions of points. In otherwords, if there are M keyframes, each having N unmatched features,searching for new features involves an operation of MN2 (O(MN2)).Unfortunately, this is a very large search operation.

One approach to find new points that avoids such a large searchoperation is by render rather than search. In other words, assuming theposition of M keyframes are known and each of them has N points, the ARsystem may project lines (or cones) from N features to the M keyframesto triangulate a 3D position of the various 2D points. Referring now toFIG. 13 , in this particular example, there are 6 keyframes 2802, andlines or rays are rendered (using a graphics card) from the 6 keyframesto the points 2804 derived from the respective keyframe. In someembodiments, new 3D map points may be determined based on theintersection of the rendered lines. In other words, when two renderedlines intersect, the pixel coordinates of that particular map point in a3D space may be 2 instead of 1 or 0. Thus, the higher the intersectionof the lines at a particular point, the higher the likelihood is thatthere is a map point corresponding to a particular feature in the 3Dspace. In some embodiments, this intersection approach, as shown in FIG.13 may be used to find new map points in a 3D space.

It should be appreciated that for optimization purposes, rather thanrendering lines from the keyframes, triangular cones may instead berendered from the keyframe for more accurate results. The triangularcone is projected such that a rendered line to the N feature (e.g.,2804) represents a bisector of the triangular cone, and the sides of thecone are projected on either side of the Nth feature. In someembodiments, the half angles to the two side edges may be defined by thecamera's pixel pitch, which runs through the lens mapping function oneither side of the Nth feature.

The interior of the cone may be shaded such that the bisector is thebrightest and the edges on either side of the Nth feature may be set of0. The camera buffer may be a summing buffer, such that bright spots mayrepresent candidate locations of new features, but taking into accountboth camera resolution and lens calibration. In other words, projectingcones, rather than lines may help compensate for the fact that certainkeyframes are farther away than others that may have captured thefeatures at a closer distance. In this approach, a triangular conerendered from a keyframe that is farther away will be larger (and have alarge radius) than one that is rendered from a keyframe that is closer.A summing buffer may be applied in order to determine the 3D map points(e.g., the brightest spots of the map may represent new map points).

Essentially, the AR system may project rays or cones from a number of Nunmatched features in a number M prior keyframes into a texture of theM+1 keyframe, encoding the keyframe identifier and feature identifier.The AR system may build another texture from the features in the currentkeyframe, and mask the first texture with the second. All of the colorsare a candidate pairing to search for constraints. This approachadvantageously turns the O(MN2) search for constraints into an O(MN)render, followed by a tiny O((<M)N(<<N)) search.

In another approach, new map points may be determined by selecting avirtual keyframe from which to view the existing N features. In otherwords, the AR system may select a virtual keyframe from which to viewthe map points. For instance, the AR system may use the above keyframeprojection, but pick a new “keyframe” based on a PCA (Principalcomponent analysis) of the normals of the M keyframes from which {M,N}labels are sought (e.g., the PCA-derived keyframe will give the optimalview from which to derive the labels).

Performing a PCA on the existing M keyframes provides a new keyframethat is most orthogonal to the existing M keyframes. Thus, positioning avirtual keyframe at the most orthogonal direction may provide the bestviewpoint from which to find new map points in the 3D space. Performinganother PCA provides a next most orthogonal direction, and performing ayet another PCA provides yet another orthogonal direction. Thus, it canbe appreciated that performing 3 PCAs may provide an x, y and zcoordinates in the 3D space from which to construct map points based onthe existing M keyframes having the N features.

FIG. 14 describes an example method 2900 for determining map points fromM known keyframes. First, at 2902, the AR system retrieves M keyframesassociated with a particular space. As discussed above, M keyframesrefers to known keyframes that have captured the particular space. Next,at 2904, a PCA of the normal of the keyframes is performed to find themost orthogonal direction of the M keyframes. It should be appreciatedthat the PCA may produce three principals each of which is orthogonal tothe M keyframes. Next, at 2906, the AR system selects the principal thatis smallest in the 3D space, and is also the most orthogonal to the viewof all the M keyframes.

At 2908, after having identified the principal that is orthogonal to thekeyframes, a virtual keyframe may be placed along the axis of theselected principal. In some embodiments, the virtual keyframe may beplaced far away enough so that its field of view includes all the Mkeyframes.

Next, at 2910, the AR system may render a feature buffer, such that rays(or cones) are rendered from each of the M keyframes to the Nth feature.The feature buffer may be a summing buffer, such that the bright spots(pixel coordinates at which lines N lines have intersected) representcandidate locations of N features. It should be appreciated that thesame process described above may be repeated with all three PCA axes,such that map points are found on x, y and z axes.

Next, at 2912 the system may store all the bright spots in the image asvirtual “features”. Next, at 2914, a second “label” buffer may becreated at the virtual keyframe to stack the lines (or cones) and tosave their {M, N} labels. Next, at 2916, a “mask radius” may be drawnaround each bright spot in the feature buffer. It should be appreciatedthat the mask radius represents the angular pixel error of the virtualcamera. The AR system may fill the resulting circles around each brightspot, and mask the label buffer with the resulting binary image. In anoptional embodiment, the circles may be filled by applying a gradientfilter such that the center of the circles are bright, but thebrightness fades to zero at the periphery of the circle.

In the now-masked label buffer, the principal rays may be collectedusing the {M, N}-tuple label of each triangle. It should be appreciatedthat if cones/triangles are used instead of rays, the AR system may onlycollect triangles where both sides of the triangle are captured insidethe circle. Thus, the mask radius essentially acts as a filter thateliminates poorly conditioned rays or rays that have a large divergence(e.g., a ray that is at the edge of a field of view (FOV) or a ray thatemanates from far away).

For optimization purposes, the label buffer may be rendered with thesame shading as used previously in generated cones/triangles). Inanother optional optimization embodiment, the triangle density may bescaled from one to zero instead of checking the extents (sides) of thetriangles. Thus, rays that are very divergent will effectively raise thenoise floor inside a masked region. Running a local threshold-detectinside the mark will trivially pull out the centroid from only thoserays that are fully inside the mark.

At 2918, the collection of masked/optimized rays m may be fed to abundle adjuster to estimate and/or correct the location of thenewly-determined map points. It should be appreciated that this systemis functionally limited to the size of the render buffers that areemployed. For example, if the keyframes are widely separated, theresulting rays/cones will have a lower resolution.

In an alternate embodiment, rather than using PCA analysis to find theorthogonal direction, the virtual keyframe may be placed at the locationof one of the M keyframes. This may be a simpler and more effectivesolution because the M keyframes may have already captured the space atthe best resolution of the camera. If PCAs are used to find theorthogonal directions at which to place the virtual keyframes, theprocess above is repeated by placing the virtual camera along each PCAaxis and finding map points in each of the axes.

In yet another example method of finding new map points, the AR systemmay hypothesize new map points. The AR system may retrieve the firstthree principal components from a PCA analysis on M keyframes. Next, avirtual keyframe may be placed at each principal. Next, a feature buffermay be rendered exactly as discussed above at each of the three virtualkeyframes. Since the principal components are by definition orthogonalto each other, rays drawn from each camera outwards may hit each otherat a point in 3D space.

It should be appreciated that there may be multiple intersections ofrays in some instances. Thus, there may now be N features in eachvirtual keyframe. Next, a geometric algorithm may be used to find thepoints of intersection between the different rays. This geometricalgorithm may be a constant time algorithm because there may be N3 rays.Masking and optimization may be performed in the same manner describedabove to find the map points in 3D space.

World Model Refinement

In some embodiments, the AR system may stitch separate small world modelsegments into larger coherent segments. This may occur on two levels:small models and large models. Small models correspond to a local userlevel (e.g., on the computational component, for instance belt pack).Large models, on the other hand, correspond to a large scale orsystem-wide level (e.g., cloud system) for “entire world” modeling. Thiscan be implemented as part of the passable world model concept.

For example, the individual AR system worn by a first user capturesinformation about a first office, while the individual AR system worn bya second user captures information about a second office that isdifferent from the first office. The captured information may be passedto cloud-based computers, which eventually builds a comprehensive,consistent, representation of real spaces sampled or collected byvarious users walking around with individual AR devices. The cloud basedcomputers build the passable world model incrementally, via use overtime. It is anticipated that different geographic locations will buildup, mostly centered on population centers, but eventually filling inmore rural areas.

The cloud based computers may, for example, perform a hash on GPS,Wi-Fi, room color histograms, and caches of all the natural features ina room, and places with pictures, and generate a topological graph thatis the topology of the connectedness of things, as described above. Thecloud-based computers may use topology to identify where to stitch theregions together. Alternatively, the cloud based computers could use ahash of features (e.g., the topological map), for example identifying ageometric configuration in one place that matches a geometricconfiguration in another place.

Exemplary Mapping Systems

FIG. 15 schematically depicts a mapping system 200 including first andsecond AR/MR systems 220, 230 according to some embodiments. The firstand second AR/MR systems 220, 230 are communicatively coupled to a cloudprocessing component 210 by first and second networks 240, 242,respectively. Although two networks 240, 242, are depicted in FIG. 15 ,the various components of the mapping system 200 may be communicativelycoupled to each other by more or fewer networks. Each of the first andsecond networks 240, 242 may be, for example, a wireless or cellularnetwork, a private communication network (e.g., mobile phone network), aLocal Area Network (LAN), a Wide Area Network (WAN), and/or othertechnology capable of enabling one or more computing devices tocommunicate with one another.

Each of the first and second AR/MR systems 220, 230 has a power pack222, 232 communicatively coupled to a wearable 224, 234 with respectiveUSB connectors 226, 236. The power packs 222, 232 may have an NVidia/ARMarchitecture, running a malleus OS. The wearable 224, 234 may have aMyriad/SHAVE architecture, running a minotaur OS. The cloud processingcomponent 210 may have a PC architecture, running a server (e.g.,Windows) OS.

Each of the first and second AR/MR systems 220, 230 can perform mappingand map synchronization on its own. Additionally, the first and secondAR/MR systems 220, 230 can perform mapping and map synchronization usingdata from the other system 230, 220 is communicated through the clubprocessing component 210. Sharing data from a plurality of AR/MR systems220, 230 increases the accuracy of mapping. However, increasing theamount of input data for mapping increases the processor load.

Exemplary Mapping/Map Synchronization Methods

Maps are not static, but are instead constantly generated, modified, andoptimize. As such, this state of maps varies over time. Further, factorssuch as data locality (i.e., the source of data for mapping operationsbeing various components such as the wearable and the power pack) andplatform constraints (e.g., processing power and memory) rendered moreefficient to distribute certain workload/jobs among various systemcomponents such as the wearable 224, the power pack 222, and the cloudprocessing component 210. The connected nature of AR/MR systems 220 andthe communication latency in the connections (e.g., network 240 and USB226) between the various components results in significant latency inorder to achieve map synchronization across component. For instance, insome AR/MR systems, the map is “locked” during each map relatedoperation, and then a copy of the updated map is distributed across thecomponents for the next operation. This latency/lag is unacceptable formany AR/MR systems. Map management takes into account different maprelated workloads at different times, and synchronization latency ofdifferent mapping system components.

Parallel processing between system components (e.g., SHAVES) can reducesystem latency. However the differences between system componentsdescribed above complicate implementation of parallel processing. Someof these complications include triggering of system components atdifferent times, different processing rates for the system components,and different data sets on which system components operate. Asynchronousparallel processing implicates various considerations, such as managinga plurality of readers and writers and operate on the same map.Minimizing the number of concurrent processes reduces system complexity,however some degree of asynchronous parallel processing improves mappingsystem performance.

Asynchronous Parallel Mapping Workflow

FIG. 16 depicts a workflow for an asynchronous mapping method 300 for amulticomponent mapping system according to some embodiments. Various mapmodification techniques involving new data and optimization can becarried out in parallel using the method 300. As described above, newdata techniques can include tracking, VIO, mapping, relocalization, mapmerge, and joint dense optimization. Map modification techniquesinvolving optimization include bundle adjustment and loop closure. Newdata techniques are efficiently performed at the system component thatis the source of the new data. Optimization techniques are processingintensive and are thus more efficiently performed at the power pack.During optimization, special consideration is required for persistentpoints and dense mapping.

At time “t” 310, a bundle adjustment (optimization) operation 320 beginsworking on a snapshot of a sparse map. Because the bundle adjustment 320is a processing intensive operation, the bundle adjustment 320 takes arelatively long amount of time ΔT 322 to complete. As discussed above,the processing intensive bundle adjustment 320 may be carried out by thepower pack.

During execution of the bundle adjustment 320, another component (e.g.,the wearable) may execute a map point deletion 330 (e.g., because a mappoint was determined to be an outlier). The map point deletion 330begins working on a later snapshot of the sparse map at time “t+1” 312.Because the map point deletion 330 is a relatively less processingintensive operation, the map point deletion 330 can be completed duringthe bundle adjustment 320. At time “t+2” 314, the wearable has completedthe map point deletion 330.

After the map point deletion 330 is completed, the system may performother operations during the bundle adjustment 320. Finally, at time“t+ΔT” 316, the bundle adjustment is completed. This workflow 300 allowsmultiple map related operations (bundle adjustment 320, map pointdeletion 330, etc.) to be executed by different components of themapping system in parallel, thereby reducing the amount of latency/lagin the mapping system. The parallel execution of multiple map relatedoperations is described in further detail below. In particular, if themap point that was deleted is also part of the bundle adjustmentoperation, there may be a conflict between the two operations (bundleadjustment 320 and map point deletion 330).

Data Conflict During Asynchronous Parallel Mapping

FIGS. 17A to 17D depict a plurality of exemplary loop closure operationsthat may result in data conflict with asynchronous parallel mapping.FIG. 17A depicts six keyrig frames 410, 411, 412, 413, 414, 415, and 416as dots in a map 401. A loop 418 is detected between keyrig frames 410and 410′.

FIG. 17B depicts closing of the loop 418 with a fixed origin 410 bymoving keyrig frames 422, 423, 424, 425, and 426 to generate new map402.

FIG. 17C depicts closing of the loop 418 with fixed origin 410. Due toasynchronous workloads, loop 438 is detected at a time corresponding tothe generation of keyrig frame 433. As such, loop 438 is closed bymoving keyrig frames 432 and 433. One or more separate workloadsgenerates keyrig frames 434, 435, and 436. The map 403 resulting fromloop closure at keyrig frame 433 followed by generation of keyrig frames434, 435, and 436 has a shape that is very different from the maps 401,402 in FIGS. 17A and 17B.

FIG. 17D depicts closing of the loop 418 while allowing movement of theorigin 410 to new position 440 according to some embodiments. This loopclosure can be performed during generation of keyrig frames 441, 442,443, 444, 445, and 446 without generating an anomalous shape. Forinstance, the map 404 in FIG. 17D is much closer to the maps 401, 402 inFIGS. 17A and 17B as compared to the map 403 in FIG. 17C.

Map management design includes recognition and resolution/reconciliationof conflicts such as these and numerous other possible mapping conflictswith asynchronous workloads. Resolution/reconciliation includes adetermination of whether the initial state used to generate a statechange is still valid, and whether we should apply the state change.These conflicts are data and time dependent, further complicating theresolution/reconciliation process in map management.

Asynchronous Parallel Mapping Workflow with Map Management

FIG. 18 depicts a workflow for an asynchronous mapping method 500 for amulticomponent mapping system with map management according to someembodiments. The mapping method 500 includes a unique timeline that ismaintained by a map manager (described below), but is not necessarilyrepresented as a time index collection of states. FIG. 18 includes threestates 510, 512, 514. The “+” operator 516 represents application of achange (e.g., “Δ0” 522) to a previous state to generate the next state.

Changes are produced by various map operations in the method 500. Forinstance, a mapping operation 520 receives as input the state atexecution of the mapping operation 520 (i.e., state zero 510) andexternal data 518. State zero 510 may be the special state with the mapis empty. The output of the mapping operation 520, as with all mapoperations in method 500, is not a new state, but rather a state change(i.e., Δ0 522). Similarly, a bundle adjustment operation 530 receives asinput the state at execution of the bundle adjustment operation 530(i.e., state one 512) and other data (not shown). The output of thebundle adjustment operation 530 is another state change (i.e. Δ1 532).Further, a plurality of other map operations 540 can output a respectiveplurality of state changes 542.

The “+” operations 516 applying various state changes (i.e., Δ0 522, Δ1532, Δ . . . 542) to previous states to generate the next state. Forinstance, state change Δ0 522 is applied to state zero 510 to generatestate one 512. Similarly, state change Δ1 532 is applied to state one512 to generate state two 514. The state changes 522, 532, 542 areapplied in order of state progression as long as there is no conflict.If there a conflict between the state and the state change is detected,the conflicts between the state and the state change areresolved/reconciled during the “+” operations 516. Conflict resolutionis implementation dependent because the types of conflicts depend on themodification being applied to the map.

System components read snapshots of the various states 510, 512, 514 andother data as may be needed for use by the various mapping operations520, 530, 540. Similarly, system components write state changes 522,532, 542 that contain the modifications to the map resulting from thevarious mapping operations 520, 530, 540. The state changes 522, 532,542 are applied shortly after being received to create new map states512, 514. Various components that execute operations dependent on mapstates can subscribe to the state changes.

Accordingly, a given map state can be determined by an initial state andin order to sequence of state changes. For instance, given an initialstate zero 510, and state changes 522 and 532, a map state can bedefined as state zero 510 “+” state change 522 “+” state change 532.Consequently, a globally agreed initial map state and ordering of statechanges allows different system components to perform mapping operationsand generate state changes while running on different platforms atdifferent rates.

A map manager determines the initial map state and ordering of statechanges, and sends/pushes/broadcasts/replicates this mapping data to allsystem components to allow asynchronous parallel mapping whilemaintaining a consistent map between all components of the system. Eachsystem component has a map manager that will eventually access all statechanges produced in the system. The ordered state changes function as avirtual bus that connects all system components and the map managerstherein.

FIG. 19 depicts an AR/MR system 600 for mapping and map synchronization.The system 600 includes a wearable 610 and a power pack 620communicatively coupled by a USB communication link 630 to each otherand to a cloud processing components 640. Each of the wearable 610 andthe power pack 620 include a map manager 612, 622, a reader 614, 624,and a writer 616, 626. Each of the map managers 612, 622, readers 614,624, and writers 616, 626 are communicatively coupled to the USBcommunication link 630, which forms a virtual bus that connects allsystem components.

The readers 614, 624 receive data from the USB communication link 630and other sources in their respective components 610, 620. The datareceived by the reader 614, 624 include state changes. The reader 614,624 sends the received data to the map managers 612, 622.

The map managers 612, 622 process the data received from the readers614, 624. The map manager 612 in the wearable 610 generates a changeorder 618 corresponding to the order of state changes from the initialstate as described above. The change order 618 is generated based onwhen the state changes are to be applied to the various states. Thisorder is generally related to the times at which the wearable mapmanager 612 receives the state changes. If more than one state changearrives at the wearable map manager 612 at one time, the map manager 612decides how to order the simultaneously writing state changes.

The map manager 612 in the wearable 610 sends the change order 618 tothe map manager 622 in the power pack 620. The change order 618 allowsthe system components 610, 620 and virtual bus 630 to functionasynchronously, such that the map managers 612, 622 can receive statechanges from the different system components 610, 620 in a sequencedifferent from the change order 618. The change order 618 allows the mapmanagers 612, 622 to apply the received state changes in an agreed-uponorder to synchronize the maps across system components 610, 620.

In some embodiments, reordering of state changes based on the changeorder 618 does not change the order of state changes generated by thesystem component including a particular map manager relative to eachother. Further, state changes can be modified to include only datarelevant to the map in a particular system component (e.g., a smallermap stored in a wearable as described below) in order to moreefficiently utilize the virtual bus 630.

The map manager 612, 622 send data to the writers 616, 626. Such datamay include state changes and, in some embodiments, the change order618. The writers 616, 626 in turn send the data to the virtual bus 630.The virtual bus 630 distributes the state changes in the change order618 between the system components 610, 620 so that each component 610,620 eventually receives all state changes and the change order 618.Because the map is not static, the system components 610, 620 constantlysend map updates to each other across the virtual bus 630. The virtualbus 630 also connects to the cloud processing component 640, which maykeep its own map for use across multiple mapping systems connectedthereto. The cloud processing components 640 may have a map manager, areader, and a writer (not shown) like those in the other systemcomponents 610, 620.

FIG. 20 depicts a wearable map manager 710 generating a change order 750by analyzing a plurality of received state changes. The state changesinclude mapping state changes 720, bundle adjustment state changes 730,and loop closure state changes 740. The state changes may be generatedby different system components. For instance, some of the mapping statechanges 720 may be generated by a wearable, and the bundle adjustmentstate changes 730 and the loop closure state changes 740 may begenerated by a power pack. Each state change can be uniquely identifiedby a compose key, which identifies the writer and a sequence count ortimestamp. For example, if each writer produces to state changes thecompose keys may be:

-   -   Mapping: MapDelta(0), MapDelta(1)    -   BundleAdjust: BundleAdjust(0), BundleAdjust(1)    -   LoopClosure: LoopClosure(0), LoopClosure(1)

The wearable map manager 710 analyzes the received state changes andgenerates a change order 750. Continuing with the example of composekeys listed above, the change order may be communicated as a singlestream of state changes that also represents the global ordering ofthose state changes. An exemplary change order is a “MapDelta(0),BundleAdjust(0), MapDelta(1), LoopClosure(0), BundleAdjust(1),LoopClosure(1)”. The other map managers and the system eventuallyreceive the same state changes in the change order 750 from the wearablemap manager 710.

FIG. 21 depicts a power pack map manager 810 applying a plurality ofreceived state changes based on a received change order 850. The statechanges include mapping state changes 820, bundle adjustment statechanges 830, and loop closure state changes 840. The state changes maybe generated by different system components. For instance, some of themapping state changes 820 may be generated by a wearable, and the bundleadjustment state changes 830 and the loop closure state changes 840 maybe generated by a power pack. The change order 850 may have beengenerated by a wearable map manager and received through a virtual bus.In order to apply the received state changes 820, 830, 840 in thesequence encoded in the received change order 850, the power pack mapmanager 810 includes a plurality of buffers 822, 832, 842 two storiesthe received state changes 820, 830, 840 until they are called up by thechange order 850. If the next state change according to the change order850 is available, the power pack map manager 810 will apply the next achange. If the next a change according to the change order 850 is notavailable, the power pack map manager 810 will wait for the next statechange to be received and operate in an asynchronous manner. If statechanges arrive before the change order 850, the power pack map manager810 will wait for the change order 850 to arrive and operate in anasynchronous manner.

The “+” operation described above for applying state changes to statesis configured to be substantially similar across system components. Thisallows state changes to be distributed and apply across different systemcomponents. The “+” operation can be configured for execution by thewearable and power pack by deleting the binaries for the device from themanifest. For cloud processing components, the “+” operation can beconfigured by deleting the cloud binaries from the manifest or explicitversioning of the “+” operator, etc.

FIG. 22 depicts a wearable map manager 910 processing a plurality ofreceived state changes. The state changes include tracking state changes920, mapping state changes 930, and bundle adjustment state changes 940.The state changes may be generated by different system components. Forinstance, some of the tracking state changes 920 and mapping statechanges 930 may be generated by a wearable, and the bundle adjustmentstate changes 940 may be generated by a power pack. The wearable mapmanager 910 generates a change order 950 from the received state changes920, 930, 940. In order to minimize locking of the map, the wearable mapmanager 910 also execute reader jobs Pre-Track 924, Pre-Map 934, andPre-Bund Adjust 944 to create snapshots of the map for the respectivestate changes.

FIG. 23 depicts a power pack map manager 1010 processing a plurality ofreceived state changes 1020 based on a received change order 1050. Thestate changes may be generated by different system components, and thechange order may be generated by a wearable. The power pack map manager1010 generates a change order 1050 from the received state changes 1020,1030, 1040. In order to minimize locking of the map, the power pack mapmanager 1010 also execute reader jobs Pre-Loop CI 1024, Pre-Pose 1034,and Pre-Cell Str 1044 to create snapshots of the map for the respectivestate changes. The snapshots may include only data needed for theparticular reader jobs. After the snapshots are taken, the map managermay execute different reader jobs on the map. Generating the snapshotsallows actual map processing to occur off-line, thereby minimizing theamount of time the map is locked for processing.

The power pack map manager 1010 executes the state changes 1020 based onthe change order 1050 and triggers downstream jobs corresponding to thepreviously executed reader jobs 1024, 1034, 1044 and the snapshotsgenerated thereby. The trigger downstream jobs include loop closure1026, trajectory updates 1036, and cell streaming 1046.

The embodiments described above facilitate asynchronous parallel mappingusing mapping systems including map managers, states changes, and changeorders to synchronize maps across system components. This reduces systemlatency/lag, thereby enabling improved real time system performance.

Cell Streaming

FIGS. 24 and 25 depict a cell streaming method in a multiple componentmapping system. This method addresses the memory limitations ofwearables by storing a smaller map 1100 in the wearable and a larger map(not shown) including the smaller map 1100 in the power pack or a cloudprocessing component (not shown).

As shown in FIG. 24 , the larger map has been divided into a pluralityof map subunits/cells 1110, 1112, and the smaller map 1100 includes afirst subset of the plurality of map subunits 1110, 1112. The smallermap 1100 is a 3×3×1 subunit 3D array, with each subunit 1110, 1112measuring approximately 7 m×7 m×7 m. In other embodiments, the smallermap (not shown) may be a 10×10×1 subunit 3D array, or a 6×6×3 3D subunitarray. The smaller map 1100 also includes a central map subunit 1112corresponding to the current location of the mapping system/user.

FIG. 25 shows streaming of cells with movement of the mappingsystem/user from the previous central map subunit 1112 to the updatedcentral map subunit 1112′. The updated smaller map 1100′ depicted inFIG. 25 includes more varieties of map subunits 1110, 1112, 1112′, 1114,1116. These new map subunits 1112′, 1114, 1116 are identical to the mapsubunits 1110, 1112 shown in FIG. 24 . For instance, each map subunits1110, 1112, 1112′, 1114, 1116 measures approximately 7 m×7 m×7 m. Whenthe mapping system/user moves to the updated central map subunit 1112′,map subunits 1114 are more than one map subunit away from the mappingsystem/user. Accordingly, a portion of the first subset of the pluralityof map subunits defining the smaller map 1100 in FIG. 24 made up of mapsubunits 1114 is deleted from the memory of the wearable.

The wearable also receives (e.g., from the power pack) a second subsetof the plurality of map subunits 1116 such that the remaining mapsubunits 1110, 1112 from the first subset of the plurality of subunitsand the second subset of the plurality of map subunits 1116 fullysurround the updated central map subunit 1112′. The second subset of theplurality of map subunits 1116 is stored in the memory of the wearablemade available by deleting map subunits 1114, as described above.

The method depicted in FIGS. 24 and 25 allows the wearable to access themap subunits needed for various mapping functions while minimizing thedemands on the limited memory in the wearable by unloading unneeded mapsubunits before loading new map subunits. The method maintains at leastone map subunit in each direction in the X-Y plane from the central mapunit. Accordingly, map subunits can be swapped while maintaining somemap data for mapping functions (e.g., tracking) during the swappingprocess. While the movement depicted in FIGS. 24 and 25 is a diagonalmovement, any other movements in the X-Y plane can be followed byupdates of the smaller map in the wearable according to the methoddescribed above.

Using the method depicted in FIGS. 24 and 25 , or other similar methods,a sparse map can be represented as: SparseMap(t)={Cell₁(t), Cell₂(t), .. . , Cell_(N)(t)}. As described above, state changes can be applied tosparse maps resulting in SparseMap(t+1)=SparseMap(t) “+” StateChange(t). When the “+” operator has a distributive property, statechanges can be applied to sparse maps as follows:

$\begin{matrix}{{{{SparseMap}(t)}\mspace{14mu}{`` + "}\mspace{14mu}{State}\mspace{14mu}{{Change}(t)}} =} & {\left\{ {{{Cell}_{1}(t)},{{Cell}_{2}(t)},\ldots\;,{{Cell}_{N}(t)}} \right\}\mspace{14mu}{`` + "}} \\ & {{State}\mspace{14mu}{{Change}(t)}} \\{=} & {\left\{ {{{{Cell}_{1}(t)}\mspace{14mu}{`` + "}\mspace{14mu}{State}\mspace{14mu}{{Change}(t)}},} \right.} \\ & {{{{Cell}_{2}(t)}\mspace{14mu}{`` + "}\mspace{14mu}{State}\mspace{14mu}{{Change}(t)}},\ldots\;,} \\ & \left. {{{Cell}_{N}(t)}\mspace{14mu}{`` + "}\mspace{14mu}{State}\mspace{14mu}{{Change}(t)}} \right\} \\{=} & {\left\{ {{{Cell}_{1}\left( {t + 1} \right)},{{Cell}_{2}\left( {t + 1} \right)},\ldots\;,} \right.} \\ & \left. {{Cell}_{N}\left( {t + 1} \right)} \right\} \\{=} & {{{SparseMap}\left( {t + 1} \right)}.}\end{matrix}$As such, state changes can be applied on a personal level, withoutaccessing the state of all the cells in the complete sparse map (e.g.,as in the wearable).

During cell streaming, a snapshot of a map subunits/cell is copied overfrom the power pack to the wearable. Due to the size of some maps, bythe time the last map subunit is received at the wearable, the first mapsubunit received by the wearable may be out of date relative to mapprocesses performed at the power pack. Using a per cell state changemethod, state changes can be applied to the first map units received bythe wearable to bring them up-to-date.

The cell streaming method described above also allows wearables toperform map related functions while storing only a portion of a completesparse map of a local environment. By streaming the map subunits fromthe power pack based on movement of the mapping system/user, memoryusage is kept to a minimum in the wearable while maintaining sufficientmap data for the wearable to perform many map functions.

Zero Copy Data Transfer

FIGS. 26 and 27 depict a data structure for zero copy data transferacross a relatively low bandwidth communication channel such as a USBconnector. Zero copy data transfer can be used in the cell swappingmechanism depicted in FIGS. 24 and 25 and described above to reducelatency in the USB communication channel between the wearable and thepower pack. Using the depicted data structure and zero copy datatransfer, the USB communication channel can write data directly into thesystem component memory that will be used in various mapping operations.This is an improvement over current systems where data from the USBcommunication channel is first written to a buffer in the systemcomponent, then written from the buffer to the system component memory.As such, zero copy data transfer reduces both memory usage and processorusage for copying data.

Zero copy data transfer uses ownership and cell state dataindicators/tags. As shown in FIG. 26 , a particular cell's ownership canbe “NONE,” “MAP,” or “USB”. Similarly, a particular cell's state can be“INVALID,” “MAP,” or “USB”. The map may be an array of cells each ofwhich has an individual owner and state. The map may also include enoughcells to cover transient situations as cells enter and leave the map.

Initially, a cell has been ownership of “NONE” and a state of “INVALID”.When the cell is being transferred over the USB connection, itsownership is set to “USB” or “Comm2” and its state is set to “USB”. Whenthe transfer is complete and the cell is being used by the system, itsownership and state are both set to “MAP”. The cells can be accessed byvarious mapping operations/jobs using a reader and a writer. Only asingle instance of a writer may be allowed in the mapping system.Multiple instances of readers may be allowed in the mapping system, butsimultaneously reading and writing is not allowed.

When a particular map operations/job begins, a framework will pass thereader and/or writer as appropriate to the corresponding systemcomponent. A cell list includes pointers to all cells currently owned bythe map and a count of those cells. At the end of the map operation/job,the writer will populate a request array. The request array instructsthe framework to perform one of three functions to each cell of the map.The invalidate requests marks cells as ownership “NONE” and state“INVALID”. The send requests marks cells for transfer as ownership “USB”or “Comm2” and state “USB”. After the transfer is complete the sendrequests marks the cells as ownership “NONE” and state “INVALID”. Adebug requests sends a cell without marking it “INVALID”. As such,during a debug, the system component does not change the cell.

Ownership is transferable between the USB communication channel (“USB”)and the system component working on the cell (“MAP”). Because ownershipcan be changed with a simple pointer operation without copying the datain the cell, changing ownership of cells being transferred is relativelylow-cost to the processor and memory.

System Architecture Overview

FIG. 28 is a block diagram of an illustrative computing system 1200suitable for implementing an embodiment of the present disclosure.Computer system 1200 includes a bus 1206 or other communicationmechanism for communicating information, which interconnects subsystemsand devices, such as processor 1207, system memory 1208 (e.g., RAM),static storage device 1209 (e.g., ROM), disk drive 1210 (e.g., magneticor optical), communication interface 1214 (e.g., modem or Ethernetcard), display 1211 (e.g., CRT or LCD), input device 1212 (e.g.,keyboard), and cursor control.

According to one embodiment of the disclosure, computer system 1200performs specific operations by processor 1207 executing one or moresequences of one or more instructions contained in system memory 1208.Such instructions may be read into system memory 1208 from anothercomputer readable/usable medium, such as static storage device 1209 ordisk drive 1210. In alternative embodiments, hard-wired circuitry may beused in place of or in combination with software instructions toimplement the disclosure. Thus, embodiments of the disclosure are notlimited to any specific combination of hardware circuitry and/orsoftware. In one embodiment, the term “logic” shall mean any combinationof software or hardware that is used to implement all or part of thedisclosure.

The term “computer readable medium” or “computer usable medium” as usedherein refers to any medium that participates in providing instructionsto processor 1207 for execution. Such a medium may take many forms,including but not limited to, non-volatile media and volatile media.Non-volatile media includes, for example, optical or magnetic disks,such as disk drive 1210. Volatile media includes dynamic memory, such assystem memory 1208.

Common forms of computer readable media includes, for example, floppydisk, flexible disk, hard disk, magnetic tape, any other magneticmedium, CD-ROM, any other optical medium, punch cards, paper tape, anyother physical medium with patterns of holes, RAM, PROM, EPROM,FLASH-EPROM (e.g., NAND flash, NOR flash), any other memory chip orcartridge, or any other medium from which a computer can read.

In an embodiment of the disclosure, execution of the sequences ofinstructions to practice the disclosure is performed by a singlecomputer system 1200. According to other embodiments of the disclosure,two or more computer systems 1200 coupled by communication link 1215(e.g., LAN, PTSN, or wireless network) may perform the sequence ofinstructions required to practice the disclosure in coordination withone another.

Computer system 1200 may transmit and receive messages, data, andinstructions, including program, i.e., application code, throughcommunication link 1215 and communication interface 1214. Receivedprogram code may be executed by processor 1207 as it is received, and/orstored in disk drive 1210, or other non-volatile storage for laterexecution. Database 1232 in storage medium 1231 may be used to storedata accessible by system 1200 via data interface 1233.

The disclosure includes methods that may be performed using the subjectdevices. The methods may comprise the act of providing such a suitabledevice. Such provision may be performed by the user. In other words, the“providing” act merely requires the user to obtain, access, approach,position, set-up, activate, power-up or otherwise act to provide therequisite device in the subject method. Methods recited herein may becarried out in any order of the recited events which is logicallypossible, as well as in the recited order of events.

Exemplary aspects of the disclosure, together with details regardingmaterial selection and manufacture have been set forth above. As forother details of the present disclosure, these may be appreciated inconnection with the above-referenced patents and publications as well asgenerally known or appreciated by those with skill in the art. The samemay hold true with respect to method-based aspects of the disclosure interms of additional acts as commonly or logically employed.

In addition, though the disclosure has been described in reference toseveral examples optionally incorporating various features, thedisclosure is not to be limited to that which is described or indicatedas contemplated with respect to each variation of the disclosure.Various changes may be made to the disclosure described and equivalents(whether recited herein or not included for the sake of some brevity)may be substituted without departing from the true spirit and scope ofthe disclosure. In addition, where a range of values is provided, it isunderstood that every intervening value, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the disclosure.

Also, it is contemplated that any optional feature of the inventivevariations described may be set forth and claimed independently, or incombination with any one or more of the features described herein.Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin claims associated hereto, the singular forms “a,” “an,” “said,” and“the” include plural referents unless the specifically stated otherwise.In other words, use of the articles allow for “at least one” of thesubject item in the description above as well as claims associated withthis disclosure. It is further noted that such claims may be drafted toexclude any optional element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely,” “only” and the like in connection with the recitation of claimelements, or use of a “negative” limitation.

Without the use of such exclusive terminology, the term “comprising” inclaims associated with this disclosure shall allow for the inclusion ofany additional element—irrespective of whether a given number ofelements are enumerated in such claims, or the addition of a featurecould be regarded as transforming the nature of an element set forth insuch claims. Except as specifically defined herein, all technical andscientific terms used herein are to be given as broad a commonlyunderstood meaning as possible while maintaining claim validity.

The breadth of the present disclosure is not to be limited to theexamples provided and/or the subject specification, but rather only bythe scope of claim language associated with this disclosure.

In the foregoing specification, the disclosure has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the broader spirit and scope of the disclosure. Forexample, the above-described process flows are described with referenceto a particular ordering of process actions. However, the ordering ofmany of the described process actions may be changed without affectingthe scope or operation of the disclosure. The specification and drawingsare, accordingly, to be regarded in an illustrative rather thanrestrictive sense.

The invention claimed is:
 1. A computer implemented method for updatinga point map on a system having first and second communicatively coupledhardware components, comprising: the first component performing a firstprocess on the point map in a first map state to generate a first mapchange, wherein the first map state is a state of the point map; thesecond component performing a second process on the point map in thefirst map state to generate a second map change; the second componentapplying the second map change to the point map in the first map stateto generate a first updated point map in a second map state, wherein thesecond map state is a state of the first updated point map; the firstcomponent sending the first map change to the second component; and thesecond component applying the first map change to the first updatedpoint map in the second map state to generate a second updated point mapin a third map state, wherein the third map state is a state of thesecond updated point map.
 2. The method of claim 1, further comprising:the second component sending the second map change to the firstcomponent; the first component applying the second map change to thepoint map in the first map state to generate the first updated point mapin the second map state; and the first component applying the first mapchange to the first updated point map in the second map state togenerate the second updated point map in the third map state.
 3. Themethod of claim 2, further comprising: the first component generating amap change order based on the first and second map changes; and thefirst component applying the second map change to the point map in thefirst map state before apply the first map change to the updated pointmap in the second map state based on the map change order.
 4. The methodof claim 2, wherein the first component applying the second map changeto the point map in the first map state includes the first componentgenerating a pre-change first map state, and wherein the first componentapplying the first map change to the first updated point map in thesecond map state includes the first component generating a pre-changesecond map state.
 5. The method of claim 1, wherein the second componentapplying the second map change to the point map in the first map stateincludes the second component generating a pre-change first map state,and wherein the second component applying the first map change to thefirst updated point map in the second map state includes the secondcomponent generating a pre-change second map state.
 6. The method ofclaim 1, further comprising: the first component generating a map changeorder based on the first and second map changes; and the first componentsending the map change order to the second component.
 7. The method ofclaim 6, further comprising the second component applying the second mapchange to the point map in the first map state before applying the firstmap change to the updated point map in the second map state based on themap change order.
 8. The method of claim 1, wherein the first process isselected from the group consisting of tracking, map point deletion, VIO,mapping, insertion of new keyframe/key rigframe, insertion of new mappoint, insertion of new observation, bundle adjustment, modification ofsparse map geometry, online calibration, relocalization, adding new orbfeature; add new BoW index; loop closure; modify sparse map geometry;map merge; and joint dense optimization.
 9. The method of claim 1,wherein the point map corresponds to a physical location in which thesystem is located.
 10. The method of claim 9, wherein the physicallocation is a room.
 11. The method of claim 9, wherein the physicallocation is a cell in a room.
 12. The method of claim 1, wherein thepoint map is a portion of a larger point map.
 13. The method of claim 1,wherein the first component is a head-mounted audio-visual displaycomponent of a mixed reality system, and wherein the second component isa torso-mounted processing component of the mixed reality system. 14.The method of claim 1, further comprising the second componentreconciling the second map change with the first map state beforeapplying the second map change to the point map in the first map state.15. The method of claim 1, the first and second components beingcommunicatively coupled to a third component, the method furthercomprising: the third component performing a third process on the pointmap in the first map state to generate a third map change; the first andsecond components sending the first and second map changes to the thirdcomponent, respectively; and the third component applying the third mapchange to the second updated point map in the third map state togenerate a third updated point map in a fourth map state.
 16. The methodof claim 15, wherein the first component is a head-mounted audio-visualdisplay component of a mixed reality system, wherein the secondcomponent is a torso-mounted processing component of the mixed realitysystem, and wherein the third component is a cloud based processingcomponent.
 17. The method of claim 1, further comprising the secondcomponent receiving the first map change from the first component beforegenerating the second map change.
 18. The method of claim 1, the secondcomponent comprising removable media for data storage.
 19. The method ofclaim 1, wherein the second process is selected from the groupconsisting of tracking, map point deletion, VIO, mapping, insertion ofnew keyframe/key rigframe, insertion of new map point, insertion of newobservation, bundle adjustment, modification of sparse map geometry,online calibration, relocalization, adding new orb feature; add new BoWindex; loop closure; modify sparse map geometry; map merge; and jointdense optimization.